COVID-19 in late pregnancy did not show the spread of the virus from mother to baby

In a study of 64 pregnant women with confirmed COVID, yesterday’s study reported that there was no vertical transmission (mother-to-baby transmission) of SARS-CoV-2, the virus that causes COVID-19. I am. JAMA network open..

Placental placement of angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) receptors (the two main ways SARS-CoV-2 enters cells) may protect the fetus in utero However, researchers have found that SARS-a mother-to-child CoV-2 antibody.

The study was led by Dr. Andrea Edrow, MD, a maternal-fetal medicine expert at Massachusetts General Hospital, funded by the National Institutes of Health (NIH), and focused on late-gestation mothers. Antibodies are generated.

“The discovery of the risk of mother-to-baby transmission of SARS-CoV-2 specific antibodies in the third trimester infection affects mothers’ vaccination,” said Edrow of Massachusetts General Hospital. Press release.. “Specifically, we emphasize that pregnant women are an important population to consider in vaccine deployment, and the optimal timing of vaccination to best support maternal and neonatal immunity. I also raise questions about. “

There is no viral load in women’s blood

Pregnant women positive for COVID suffered from illnesses ranging in severity from asymptomatic to severe. The researchers compared them to 63 pregnant women without COVID infection and 11 non-pregnant women of reproductive age who were hospitalized with COVID. Denise J. Jamieson, MD, MPH, and Sonja A. Rasmussen, MD, MS wrote: Commentary, These three groups allow comparison of transplacental antibody metastasis, placental pathology, and viral load antibody response during pregnancy.

No infants were SARS-CoV-2 positive in this study.

“This study provides some reassurance that SARS-CoV-2 infection in the third trimester is unlikely to cross the placenta and reach the foetation, but further studies to confirm this finding. “We need to do this,” said director Diana W. Bianchi, a doctor of medicine. NIH National Institute for Child Health Development news release..

In their commentary, Jamieson and Rasmussen add, “This supports previous studies that found that intrauterine devices are possible but uncommon.”

The researchers measured SARS-CoV-2 viral load in 62 pregnant women infected with COVID, 45 pregnant women without COVID, and all infants born to women in both groups. Respiratory viral load was measured in 44 (71.0%) infected women and 34 (75.6%) uninfected women, with detectable levels found in 11 women. Everyone was COVID-19.

However, pregnant women were free of the virus in their bloodstream and cord blood. Of the 88 placenta tested, researchers did not find SARS-CoV-2 RNA, probably due to the location of the ACE2 and TMPRSS2 receptors.

Viral load was not significantly associated with placental pathology, but detectable levels in COVID-infected patients were associated with higher anti-receptor binding domain (RBD) immunoglobulin G (IgG) antibody titers. (0.79 Titer vs. 0.29 Titer; P = 0.02). Researchers suggest that pregnancy may have enhanced the cytotoxic cellular response of the maternal immune system to the virus, but further research is needed.

Lower than expected antibody metastasis

Placental transfer of SARS-CoV-2 antibody was significantly lower than expected. Researchers have assumed a code-to-maternal (c to m) antibody ratio of 1.5, which is the value of pathogens such as whooping cough, influenza, and measles.

However, in the test, of the 37 pregnant women with COVID-19, 24 had detectable anti-RBD IgG antibodies in their blood, but only 2 in their cord blood (c-to-). m ratio, 0.08). Anti-nucleocapsid IgG was present in the blood of 26 women and 22 cord blood (c-to-m ratio, 0.85).

By comparison, influenza-specific antibodies showed normal and expected transfer levels. Perhaps this is affected by vaccine-induced antibodies and native antibodies, or SARS-CoV-2 specific antibodies have different glycosylation qualities than other antibodies and affect protein interactions. Is guessing.

The commentary states, “It is unclear whether the inefficient transplacental transfer of antibodies observed by Edrow et al. Will extend to future SARS-CoV-2 vaccine-induced antibodies, but it is unlikely. Therefore, we emphasize the sensitivity of infants. Infants are eligible for SARS-CoV-2 vaccination. “

Data from Centers for Disease Control and Prevention Infants under 2 months account for 20% of COVID-related hospitalizations in children under the age of 18, as announced in August. In addition, the commentary states that COVID-19 infection may be associated with an increased chance of preterm birth.

In yesterday’s study, women with COVID had two fetal deaths at weeks 22 and 35, one for placental abruption and early labor in symptomatic patients, and the other for asymptomatic women. It was a miscarriage.